This part of ISO/IEC 9314 specifies the Single-mode fibre Physical Layer Medium Dependent (SMF-PMD) requirements for the Fibre Distributed Data Interface (FDDI).

FDDI provides a high bandwidth (100 megabits per second) general purpose interconnection among computers and peripheral equipment using a fibre optic waveguide as the transmission medium. The FDDI may be configured to support a sustained transfer rate of approximately
80 megabits (10 megabytes) per second. The FDDI may not meet the response time requirements of all unbuffered high speed devices. The FDDI establishes the connection among many stations distributed over distances of several kilometers in extent. Default values for FDDI were calculated on the basis of 1000 physical connections and a total fibre path length of 200 kilometers (see the MAC Standard – ISO/IEC 9314-2 or ISO/IEC 9314-8).

The FDDI consists of:

1) The Physical Layer Medium Dependent (PMD) is specified in four alternative standards:

a) ISO/IEC 9314-3 (FDDI PMD) corresponding to multimode fibre (MMF) which actually
means "FDDI MMF-PMD".
b) This standard ISO/IEC 9314-4 (SMF-PMD) which contains the requirements for singlemode
fibre (SMF) physical connections between stations.
c) ISO/IEC 9314-9 (FDDI LCF-PMD), an alternative lower cost multimode fibre (LCF) for
shorter distances.
d) ISO/IEC 9314-10 (FDDI TP-PMD), a copper twisted pair (TP) alternative.
An FDDI ring can be made up of all these alternatives. (For some restrictions see 6.4).
The PMD provides all services necessary to transport a suitably coded digital bit stream
from station to station. The SMF-PMD specifies the point of interconnection
requirements for FDDI stations and cable plants at both sides of the Media Interface
Connector (MIC) for conforming stations utilizing single-mode fibre.
SMF-PMD includes the following:
i) The optical power budgets for two (2) categories of Active Output and Active Input
Interfaces using single-mode fibre optic cables and optical bypass switches
ii) The MIC Receptacle mechanical mating requirements including the keying features
iii) The single-mode fibre optic cable requirements
iv) The services provided by PMD to PHY and SMT

2) A Physical Layer Protocol (PHY), which provides connection between multimode or singlemode
PMD and the Data Link Layer (DLL). PHY establishes clock synchronization with the
upstream code-bit data stream and decodes this incoming code-bit stream into an
equivalent symbol stream for use by the higher layers. PHY provides encoding and
decoding between data and control indicator symbols and code-bits, medium conditioning
and initializing, the synchronization of incoming and outgoing code-bit clocks, and the
delineation of octet boundaries as required for the transmission of information to or from
higher layers. Information to be transmitted on the interface medium is encoded by the PHY
into a grouped transmission code.

3) A Data Link Layer (DLL), which controls the accessing of the medium and the generation
and verification of frame check sequences to assure the proper delivery of valid data to the
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higher layers. DLL also concerns itself with the generation and recognition of device
addresses and the peer-to-peer associations within the FDDI network. For purpose of the
PHY, references to DLL are made in terms of the Media Access Control (MAC) entity, which
is the lowest sublayer of DLL.

4) A Station Management (SMT), which provides the control necessary at the station level to manage the processes underway in the various FDDI layers such that a station may work cooperatively on a ring. SMT provides services such as control of configuration management, fault isolation and recovery, and scheduling procedures.

This part of ISO/IEC 9314 is a supporting document to ISO/IEC 9314-1 which should be read in
conjunction with it.

The SMT document ISO/IEC 9314-6 should be consulted for information pertaining to
supported FDDI station and network configurations.

The set of FDDI standards specifies the interfaces, functions and operations necessary to
insure interoperability between conforming FDDI implementations. This part of ISO/IEC 9314 is
a functional description. Conforming implementations may employ any design technique which
does not violate interoperability.